The present invention generally relates to high pressure chamber doors seals, and, more particularly, to a chamber door that utilizes dual seals and features a leak detection system.
Liquid carbon dioxide dry cleaning systems have recently been developed in response to the environmental, health and safety concerns that are associated with systems that utilize perchloroethylene (xe2x80x9cpercxe2x80x9d) or petroleum-based solvents. Liquid carbon dioxide is a solvent that is an inexpensive and an unlimited natural resource. Furthermore, liquid carbon dioxide is non-toxic, non-flammable and does not produce smog. Liquid carbon dioxide does not damage fabrics or dissolve common dyes and exhibits solvating properties typical of more traditional solvents. Its properties make it a good dry cleaning medium for fabrics and garments. As a result, several dry cleaning systems utilizing carbon dioxide as a solvent have been developed.
An example of a liquid carbon dioxide dry cleaning system is presented in commonly owned U.S. Pat. No. 5,904,737 to Preston et al. The system of the Preston et al. ""737 patent, which also may be used to clean mechanical parts or electrical components, features a chamber within which the items to be cleaned are placed. The interior of the chamber is accessed via a hinged door that seals when the system is in use. The chamber interior is equipped with a number of jets that are selectively in communication with a high pressure supply of liquid carbon dioxide. At the beginning of the cleaning process, the chamber is evacuated and pressurized to an intermediate pressure of approximately 70 psi. The chamber is then pressurized to approximately 650 to 690 psi as it receives liquid carbon dioxide at a temperature of approximately 54xc2x0 F., a temperature at which carbon dioxide acts as an effective solvent. Liquid carbon dioxide is then circulated through the chamber via the jets so that the items therein are agitated and cleaned.
While the system of the Preston et al. ""737 patent agitates by jets, a variety of other chamber agitation arrangements exist. For example, the cleaning chamber may feature a rotating drum (known as the fall-and-splash technique) or a source of gas bubbles. Regardless of the agitation technique of the system, however, the chambers are pressurized so that they may contain liquid carbon dioxide at an appropriate temperature. As such, it is critical for all liquid carbon dioxide (or other solvents requiring high pressure) dry cleaning systems to possess chambers with doors that may be effectively sealed.
Prior chambers typically employ a large rubber O-ring seal between the chamber opening and the chamber door. The O-ring is compressed when the chamber door is closed so that an effective seal is formed. Such an arrangement, however, fails to provide a backup or secondary seal in the event that the O-ring fails. Furthermore, such a sealing arrangement may fail without warning. In such a situation, the liquid carbon dioxide could leak into the cleaning plant, which is undesirable from a safety standpoint.
Accordingly, it is an object of the present invention to provide a high pressure chamber door seal that features a primary seal and a secondary seal.
It is a further object of the present invention to provide a high pressure chamber door seal that features a leak detection system.
It is a further object of the present invention to provide a high pressure chamber door seal that provides a warning to the system operator when the primary seal has failed.
It is still a further object of the present invention to provide a high pressure chamber door seal with a primary and secondary seal that resists dry ice formation between the primary and secondary seals.
It is still a further object of the present invention to provide a high pressure chamber door seal with a primary and a secondary seal that prevents exposure of the secondary seal to high pressure.
These and other objects of the invention will be apparent from the remaining portion of the Specification.
The present invention is directed to a seal for a high pressure chamber opening. A cylindrical element featuring a circumferential flange is positioned around the opening of the high pressure chamber. The flange features a primary O-ring seal circumferentially surrounding the chamber opening. A secondary O-ring seal circumferentially surrounds the primary O-ring seal. A door is clamped to the circumferential flange so as to cover the opening and the primary and secondary seals. As a result, the opening is sealed and an annular passage is defined between the primary and secondary seals.
If the primary seal begins to leak, the pressure within the annular space will increase. A port is formed in the cylindrical element so that the annular passage between the seals may communicate with a pressure switch. The switch is activated when the pressure in the annular space rises above approximately 10 psi. The switch, when activated, sends a signal to the user display so that a warning message or other alarm may be provided. The system operator may then inspect and repair the faulty primary seal prior to the next chamber pressurization. The port of the cylindrical element also communicates with a relief valve that vents to the exterior of the building housing the system when the pressure in the annular space rises above approximately 70 psi. By allowing the pressure in the annular space to rise to over 60 psi, the arrangement prevents or minimizes the formation of dry ice. Dry ice is damaging to the secondary seal. By venting the annular space when the pressure rises above a predetermined level, the arrangement prevents damage to the secondary seal and thus avoids leakage of fluid into the building.
For a more complete understanding of the nature and scope of the invention, reference may now be had to the following detailed description of embodiments thereof taken in conjunction with the appended claims and accompanying drawings.